Interdiffusion and Kirkendall Effect in Cu–Sb Alloys

Abstract

Interdiffusion coefficients in copper-rich copper-antimony solid solutions containing up to 5 at% of Sb have been determined by Matano’s method in the temperature range between 919 and 1040 K using semi-infinite diffusion couples consisting of pure copper and Cu–Sb alloys with the Kirkendall markers. From the interdiffusion coefficient and the marker shift, the intrinsic diffusion coefficients have been determined at the marker positions, 1.0 and 1.7 at%Sb. Using thin plate couples, the intrinsic diffusion coefficients in Cu-0.6 at%Sb alloy at 1005 K have been determined by Heumann’s method. From the value of the intrinsic diffusion coefficient of copper in the infinite dilution of Sb and the tracer diffusion coefficients of Sb and Cu in pure Cu, the vacancy flow factor for the interdiffusion in Cu–Sb alloys at 1005 K has been calculated to be −1.20−0.28+0.22, which suggests a strong interaction between an antimony atom and a vacancy. Combining the present result on the vacancy flow factor with the previous experimental data on the enhancement factor of solvent diffusivity by the addition of solute atoms, the correlation factor and the jump frequency ratios in the five-frequency model have been estimated. The correlation factor for the impurity diffusion of Sb in Cu thus obtained is about 0.1 at 1005 K, which indicates highly correlated jumps of an antimony atom to a vacancy.